Train control



Nov. 1, 1927. 1,647,968

w. K. HOWE ET AL.

TRAIN CONTROL Filed July 26, 1923 8 Sheets-Sheet 1 Nov.

W; K. HOWE ET AL.

mm: CONTROL Filed July 26, 1925 8 Sheets-Sheet 2 and m: mm

AT'ILORNEY mawi W. K. HOWE ET AL TRAIN CONTROL Nov. 1, 1927.

Filed July 26, 1923 8 Sheets-Sheet 3 IN ENTORS ATTORNEY Nov. 1, 1927. I 1,647,968

w. K. HOWE ET AL.

TRAIN CONTROL Filed y 1923 8 Sheets-Sheet 4 FIQS W lNV TORS .42

TT'ORNEY Nov.

w. K. HOWE T AL.

TRAIN CONTROL Filed July 26, 1923 8 Sheets-Sheet 6 WM Mm FIG. 1 6.

aa o ass AITTORNEY 8 Sheets-Sheet 7 W. K. HOWE ET AL.

TRAIN CONTROL Filed July 26, 1923 Nov. 1, 1927.

Fl ca.

,1 ATTORNEY Nov. 1, 1927.

1,647,968 w. HOWE ET AL.

TRAIN CQNTROL,

i e y 26, 1923 8 Sheets-Sheet 8 F: G. 17. 7

, v fihmmk 8 ConRe l. 285

and IndGroup R Gt Patented Nov. 1, 1927.

v P A T NT OFFICE.

\VINTHROP K. HOWE AND CHARLES S. BUSHNELIQOF ROCHESTER, NEW YORK, AS- SIGNORS T GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK.

TRAIN CONTROL.

Application filed July 26, 1923. Serial No. 658,898.

This invention relates to train control systems designed to give full protection under the varying operation conditions encountered in practice.

In accordance with this. invention, it is proposed to communicate. or transmit the desired controlling influences from the trackway to the moving trains by a means of the inductive non-physical contact type which is continuously effective and affords what is conveniently termed continuous inductive control; impose upon the train at all times predetermined speed restrictions which are automatically varied in accordance with traflic conditions and the location of the train so as to be adequate for safety and at the same time suitable for providing a high degree of facility of train movement, due

allowance being made for the variable,

lengths of blocks commonly encountered in practice; to require the engineer to acknowledge by a positive act each unfavorable signal indication, either caution or stop, which is given by the trackway fixed signals, or be suitably penalized for his neglect; to permit the engineer under automatically imosed restrictions to manually cut out or render inefiective the automatic control of the train while traveling in unequipped or non-signalled territory, a distinctive indication in the cab signifying that the train is traveling without protection being continuously displayed while the train is in such unsignalled territory, and the automatic control being automatically restored'as soon as the train again comes into equipped or signalled territory; to give at times cab signal indications which correctly show the existing traflic conditions ahead, whether clear, or caution, these cab signal indications being automatically changed instantly as the trafiic conditions become more favorable; to

give the engineer a reliable warnin signal v prior to every automatic brake app ication,

P if desired, so as to facilitate handling of the train by the engineer safely and with the least delay; to provide a suitable penalty for failurenon the part of the engineer to gov ern his train properly in accordance with the information provided; to make provision for manual adjustment of the apparatus on the locomotive or other vehicle so that it may be used in either freight or passenger service as desired; and in general make adequate provision for the various features of automatic, manual, and combined automatic andmanual control needed to satisfy the varying and peculiar requirements of an automatic train speed control system adaptable to tions.

Other objects, purposes, and characteristic features of the invention will appear as the description thereof progresses.

In describing the invention in detail, reference will be made to the accompanying drawings, in which Figure 1 shows a side elevation of a pony truck of a typical locomotive, together with the outer .casing containin the carcarried practical railroad operating condiapparatus of the present invention bolted thereto, part of which is broken away to illustrate how the mechanism casing is sprmg supported therein;

Fig. 21s'af1'ont elevation of the apparatus shown in Fig. 1, portions thereof being omitted for clearness;

Fig. 3 is a plan view of one compartment and a portion of the other' compartment of the mechanism casing with the cover removed, and shows 'a portion of the train control apparatus contained therein;

Fig. 4 is a sectional view taken on the line 4-4, Fig. 3, as viewed in the direction of the arrows, and shows the speed responsive de vice and cam operating gearing;

' Fig. 5 is a similar view taken on the line 55, Fig. 3;

Fig. 6 is an enlarged sectional elevation taken on the line 66, Fig. 5;

Fig. 7 is an enlarged sectional view taken on the line 77, Fig. 3, as viewed in the di rection of the arrows;

Fig. 8 is a section taken on the line 88, Fig. 3, as viewed in the direction of the arrows, and. shows the normally closed speed-distance or cam-governor contacts;

Fig. 9 is a section taken on the line 9-9, Fig. 3, and shows normally open speed-dis ta-nce contacts; i

Fig. 10 shows the distance contacts;

. Fig. 11 shows the speed contacts operated by the speed responsive device;

Fig. 12 illustrates a preferred form of carca-rried relay, which is provided with contacts similar to the contacts shown in Figs. 8to 11;

Fig. 13 is a plan view of the relay shown in Fig. 12;

Fig. 14 shows diagrammatically a section not of trackway with the necessary trackway apparatus and wiring for a train control system embodying the present invention, and also illustrates conventionally the receiving and amplifying apparatus of the car-carried apparatus including a three-positlon main control relay;

Fig. 15 is a simplified wiring diagram of the car-carried apparatus showing the various relays, cam operated contacts and brake control device in a conventional manner;

Fig 16 illustrates a more complete form of the E. P. V. and IVS group of the wiring diagram shown in Fig. 15, which is employed for a locomotive used in both passenger and freight service; and v Fig. 17 shows a modified type of car-carried apparatus similar to that illustrated in Fig. 15, in which no acknowledgment of a caution or a danger'signal is required.

Generally speaking, in practicing the present invention,-alternating current is transmitted down one of the track rails through the usual track relay (or the axles of a train, if the block happens to be occupied) back through the other rail, this current corresponding to the usual track circuit current and conveniently referred to as loop circuit current; and another alternating current,

preferably of the same frequency but displaced in phase as much as possible from the first mentioned current is transmitted through said two track rails in multiple and back over a return wire, this other current being called the simplex circuit current. These currents in the track rails are detected or picked up on the car by magnetic induction, amplified, and then used to control a suitable two-element or polyphase alternating current relay. These currents in the track rails are controlled by the usual track circuits so that their existence and phase relation in any given block depends upon the proximity of a train ahead. The loop circuit current and the simplex circuit current in the track rails are separately detected or picked up by suitable receiving devices on the vehicle, amplified, and then used to control a two-element or polyphase alternating current relay or equivalent electro-responsive device. This relay governs the cab signal indications, the speed governed brake control apparatus, and the other devices on the car used in attaining the results contemplated by this invention.

In describing the invention in detail, the apparatus will first be described, after which the operation of the system and the manner in which the different parts cooperate will be explained.

Structure of car-carried apparatus (mou/ntz'ng and transmitting connection).

In Figs. 1 and 2 has been shown in dot and dash lines a skeleton outline of a portion of a pony truck of a locomotive, showing the main frame 1, a cross beam 2 mounte thereon in any suitable manner, and a journal box 3 in which is journaled the axle 4 for the car wheel 5. The track rail is designated 6. The outline of the locomotive cylinder 9 is shown to illustrate that sufficient clearance is provided for the apparatus presently to be described.

Mechanism casing8.-TO the cross beam 2 is fastened a bracket 7, which in cooperation with another bracket 8 attached to the main frame 1, supports the outer casing or housing 10 for the car-carried apparatus, this outer casing being bolted to these brackets by bolts 11. This outer casing 10 is provided with a hinged cover 12, having a gasket in a groove in the edge thereof to fit ti htly on the upper edges of the casing; and this cover is held closed by suitable spring hasp fasteners 14 (only one being shown), which may be locked or sealed in the usual way.

It is essential to protect the relays and other sensitive devices in the mechanism casing 18 against the shock, jar and vibration to which it is necessarily subjected when carried on a locomotive or other railway vehicle. This protection may be afforded in various ways and the particular expedient adapted is not material to the present invention. In the specific construction illustrated, which is not claimed in this application, the inner mechanism casing 18 is yieldingly supported within the outer casing 10 upon cushioning springs. As shown in Fig. 1, the inner casing 18 is supported at each corner by two opposing compression springs 16 and 17, preferably under some initial tension depending upon the weight of the inner casing. The upper spring 16 is supported between two projecting lugs 20 and 21, the lower lug 21 being integral with the inner mechanism casing 18 and the upper lug 20 integral with the outer casing 10. The lower spring 17 is interposed between the middle lug 21 and a pad or boss 22 on the bottom of the outer casing 10. The ends of these springs fit over bosses on their respective supporting lugs. The boss in the upper lug 20 is preferably made adjustable by a bolt and lock nut as shown.

In addition to the spring su port just described, it is considered desira 1e to provide frictional resistance opposing the movement of the inner casing 18 with respect to the outer casing 10 so as to reduce the am litude of vibration, absorb the energy ten ing to produce continued oscillation, and in general stabilize the inner casing. As shown, a fiat spring 23 is fastened at its lower end to the outer casing 10, and the upper end of this spring is faced on both sides with pads 24 of suitable friction material, such as commonly used for automobile brake linings. A

strap or loop 25 is fastened to the inner casstrap respectively, this strap being preferably resilient or spring supported to yieldingly maintain the deslred pressure between the friction surfaces. One of these springs 23 and associated parts is preferably located ateach side and end of the inner casing 18. It will be evident that these springs 23 and their associated friction pads provide frictional opposition to vertical and lateral movement of the inner casing 18 with respect to the outer casing 10.

Transmi98i0n.The system of. this invention involves a driving connection to the car wheels; and while this driving connection may be provided in various ways, in the particular'arrangement shown, a spiral gear 27 isbolted to the outer end of the pony truck axle 4. Surrounding this gear 27 is a casing 28, made intwo halves bolted together for the purposes of assembling. This gear casing 28 is journaled on the pony truck axle 4 so that the axle may turn while the casing remains stationary. An upstanding bracket 29 is bolted to this casing 28 and has sliding fit with a hole in the outer end of an L- shaped brace 30 which is bolted to the journal 3 for the pony truck axle. These parts hold the gear casing 28 from turning. The gear casing 28 is provided with bearings for a vertical shaft 31, to which is fixed a spiral gear 32 meshed with the gear 27. The casing 28 is in practice packed with a suitable lubricant, screw plugs being provided for filling and draining this casing.

The rotation of the vertical shaft 31 is mmmunicated through a suitable universal and telescoping connection to a driven shaft 33 journaled in the inner mechanism casing 18, as shown in Fig. 4. In the construction illustrated, the vertical shaft 31 is connected by an enclosed universal joint 34 of the usual construction to a lower intermediate shaft 35, preferably tubular, which has a telescoping driving connection to an upper intermediate shaft 36, inturn connected by a universal joint37 to the driven shaft 33: g This driven shaft 33 is protected by a hollow boss 38 integral with the bottom of the outer casing 10 (see'Fig. 1). and isjournaled in a bearing sleeve 39 (Figs. .3 and 4) within a hollow boss 40 integral with the bottom of the inner casing 18. Thus, the upper end of the driven shaft 33 follows the movement of the inner casing .18, and to accommodate this movement and keep out dirt and other foreign matter, a diaphragm or packing is preferablyemployed between the boss 38 and said shaft 33. It will be evident that the telescoping and universal connection between the shafts 31 and 33 accommodates the vertical and lateral movement of the pony truck axle with respect to the frame on which the mechanism casings are mounted, as well as movement of the mner casmg 18 upon its cushioning springs.

Speed control apparatus.

This apparatus is all carried in the inner mechanism casing 18. This casing is preferably divided by a vertical partition 19 into two compartments, a gear compartment shown at the left in Fig. 3, and an instrument compartment at the right in Fig. 3. In the gear compartment is a centrifugal speed responsive device, cam operating gearing and its control mechanism; and in the instrument compartment are various contact units, relays, and the amplifying equipment. These various devices will be described separately.

Speed responsive device-This device, designed to determine the actual running speed of the vehicle at all times, as illustrated, is of the type disclosed in the patent to Howe No. 1,334,902 of March 23, 1920. This speed responsive device S, sometimes called a governor, is mounted on the upper end of the driven shaft 33. In the particular construction illustrated, an inverted cup or sleeve 43 is secured to the upper end 'ofthe driven shaft 33. This sleeve 43, which turns with the rotation .of the pony truck wheel, has

centrifuge arms 45 having corresponding ends connected by cylindrical members 46.

Slidably supported on an upstanding shaft- 48 which is fixed to the sleeve 43, is a collar 50 having extending hornshaped cams 51. This sliding collar 50 and cams 51 are forced to the extreme upper position by the compression sprin 52, and thereby cause the centrifugal weights 46 to assume a position near the shaft 48. The upper cylindrical members 46 are pivc-tally supported and thereby form rollers to constitute a substantially frictionless engagement with the cams 51.

The top part of the collar 50 is formed with a circumferential groove in which fits a rotatable ring 53, preferably provided with hearing balls. Near the lefthand side of the mechanism casing (as shown in Fig. 4) is a speed shaft 54, which is pivoted in a bearing 55 in the partition 19 and in suitable bearing bosses 56 (see Fig. 3) in the ends of this casing. Pinned to this speed shaft 54 1s a speed arm 57 (Fig. 4), which has a bi- 45 to take a position away from the axis of this device depending upon the speed at which it is driven, this action being due to the centrifugal force acting on these arms and as opposed by the spring 52 actlng on them through the horn-shaped cams 51. The shape of the horn-shaped cams 51 is such that'the angular displacement of the speed arm 57 is substantially un form for all changes of speed for WhlCh this centrifugal device 5 has been designed.

0am operating geam'mg.-The sleeve 43 on the driven shaft 33 is formed with teeth to constitute aworm (Fig.4); and this worm 65 meshes with a worm gear 66 secured to a shaft 67 (Figs; 3 and 4) extending horizontally along the bottom of the inncr caslng 18 and supported in suitable bear ngs as shown. To this shaft 67 is pinned a pinion 70 operatively engaging a g-rar 71 fastened to the shaft 72 pivotally supported in suitable bearings, and having a pinion 73 fastened thereto. This pinion 73 engages the teeth of a gear 74 fastened to a shaft 75 similarly supported in suitable bearings, and hav ng a pinion 76 fastened thereto. Tl'llS pinion 76 is continually in operative engagement with a gear 77 pinned to the driving shaft 78. The driving shaft 78 extends entirely through the gear compartment, and 1s rotatably supported in a bearing boss/79 of the partition 19 and a bearing 80 in the outside wall of the mechanism casing.

A shaft 84, conveniently designated the low cam shaft. extends entirely through the mechanism casing and is supported in a hearing boss in the outside wall of the casing. This shaft is mounted to turn freely in a long hollow shaft or sleeve 86, which Wlll for convenience be called the high cam sleeve hereinafter. This sleeve 86 is rotatably supported in a bearing 87 in the partition 19, and is limited against endwise movement by the collar 83 and a gear 112.

It is proposed to provide means whereby the high cam sleeve 86 may be started when traffic conditions change from clear to can tion and continue to turn this shaft to a predetermined point and maintain it there until traffic conditions are again clear. Similarly. substantially identical means are proposed for turning the low cam shaft 84 from the time that traffic conditions change from clear or cautionas the case may be, to danger until a suitable minimum speed position has been reached and maintain said shaft in such position until traffic conditions change either to caution or to clear. This apparatus may conveniently be called the cam starting and operating mechanism, and since both of these mechanisms are substantially the same only one of them, namely. the high cam mechanism, will be described in detail, the corresponding parts of the other being (Jam starting nwckanism.-To the driving shaft 78 is fastened a pinion 90 (Figs; 3, 4'and '7), between which and the retaining collar 91 is pivotally supported a gear frame made up of a sleeve 92 and an extending arm 93. This arm 93 carries-a gear 94 continually in mesh with the pinion 90, and a pinion 95 continually in engagement with the gear 94. The sleeve 92 of the gear frame is provided with another extending arm 96,

which has its ends bifurcated. Projecting from the outside wall of the mechanism casing are lugs 97 which support the back yoke 98 and cores 99 of the high cam starting magnet HCS. On .the cores 99 are coils 100 connected and energized in a manner hereinafter described in the operation. Thecorcs 99 are spanned by an armatur 101, which is slidably supported on non-magnetic pins 102 projecting from the top of these cores. The middle of the armature is connected to the bifurcated end of the arm 96 extending from the gear frame by a con necting rod 103. this rod being ivotally supported in said bifurcated end by a pin 107. The lower end of this connecting rod 103 is enlarged, and is urged upwardly bya spring 104 surrounding a stud 105 fastened in the boss 106 extending from the bottom of the casing. To the high cam sleeve 86 is.fastened a large gear 108, which is provided with a mutilated portion 109, and is rigidly held in place on this sleeve 86 by a set screw 110, or the. like. This gear 108 is disposed directly over the pinion 95, and is adapted to be turned thereby when this pinion is in its operative or raised position.

With the railway vehicle equipped with the apparatus thus far described and moving along the track, the speed responsive device S is continually rotated and drives the driving shaft 78, and likewise the pinion 95 through the chain of gears heretofore described. Under normal clear traffic conditions, as hereinafter described, the coils 100 of the cam starting magnet are energized. If the coils 100 are now for any reason deenergized, the attraction between the cores 99 and armature 101 ceases, and the spring 104 moves the arm 96 upward, thereby causing engagement between the pinion 95 and the mutilated gear 108. As the train proceeds along the track, this mutilated gear 108 is rotated until the pinion 95 assumes a position in the mutilated portion 109, after which no further rotation of the mutilated gear 108 takes place and the gear is maintained in this position until the pinion 95 is again brought out of engagement with the mutilated gear 108. If for any reason the coils 100 are again energized, the pinion 95 will be retracted from the mutilated gear 108, whereby this gear is again returned to its initial position as shown in Fig. 4 by suitable cam restoring means presently to be described.

0am restoring mechanism.'-A pinion 112 is fastened to the high cam sleeve 86 by a set screw 113 (Figs. 3, 5 and 6). Directly below this pinion 112 and projecting from a boss on the partition 19 of the mechanism casing is a journal pin 114 secured by a cross pin 117. Pivotally supported on this pin is a gear sector 115, having an extending lug or foot 116 provided with curved ends which are adapted to be engaged by initially tensioned spring devices provided with stops.

These spring devices comprise striking blocks 118 and 119, having overlapped ex-. tensions also pivoted on the pin 114 and retained in place by a washer 120 secured by a cross pin 121. These striking blocks have their ends resting on bosses 122 and 123. The bosses 122 and 123 are of such a height that the striking blocks 118 and 119 when resting on the bosses just contact withthe curved ends of the foot 116 of thegear sector. In the striking blocks are provided holes to receive upstanding guides 124 and 125,. which are provided with compression springs 126 and 127 having their lower ends resting in countersunk portions in the striking blocks. The springs 126 and 127 are initially tensioned and maintained in this condition by heavy washers 128 and 129 fastened by cross pins 130 and 131.

By looking at Fig. 5 it is readily apparent how the cam restoring mechanism can urge the high cam sleeve in a predetermined position and maintain it there while the cam starting magnet HUS is energized, regardless of whether or not the pinion 95 is rotating at the time. To make this more clear,

1 let us assume that the gear sector 115 has been moved to one of its extreme positions by the pinion 112. Under this condition, either the spring 26 or 127, as the case may be, will be further tensioned because the curved ends of the foot 116 lift up the striking block under this particular spring, there-- by further compressing the spring, all of which does not afi'ect orchange the tension of the other spring because it is resting on its upstanding boss.

if the high cam sleeve 86 is now released and the pinion 112 is freeto turn, the tension of the compressed spring will force its corresponding striking block 118 or 119 downward against the boss 122 or 123, thereby returning the gear sector 115 to its normal position as shown in the draw ngs. In other words, if the gear sector 115 is moved back and forth from its normal position as shown, first one and then the other of the striking blocks 118 and 119 will be lifted from their respective seats and will compress the corresponding spring, and when this sector 115 is released it will again return to its normal position.

The cam starting mechanism and cam I'e storing mechanism, just described, are those associated with the high cam sleeve 86, and are adapted to turn this sleeve when, trafiic conditions demand its turning, and again return it to its normal position when traflic conditions clear up. Similar apparatus is.

casing containing the governor, cam starting and cam restoring mechanism is preferably filled with oil so that this apparatus always will be lubricated and protected from mois ture and other detrimental agencies.

'Contact am'ts. In the instrument compartment above mentioned are contained a number of contact units of different typesand performing different functions. These contact units are operated or controlled by the-speed shaft 54, the low cam shaft 84, and the high cam sleeve 86, these shafts extending from the gear compartmentthrough the partition 19 into the instrument compartment, as shown in Fig. 3. Since the gear compartment contains lubricant and it is desirable to keep this lubricant out of the instrument compartment, suitable means, such as felt packings, is preferably provided at the points where these shafts pass through the partition.

There are a number of these contact units. many of which are constructed the same and difier from each other only in the shape or size of parts. For convenience in explanation, these units are divided into types according to their structure or function: and

these distinctive types will now be separately described.

Speed-distance contact um'tr- -This unit is designed to determine the relative position of the speed shaft 54 and the cam shaft 84 or the cam sleeve 86, as the case may be.

Fig. 8 shows one of these speed-distance units as applied to the high cam sleeve 86, a plan view of this same unit being shown inFig. 3. A specially shaped plate, herein called the high cam H, is fastened to the sleeve 86 by a set screw 135 or equivalent means. The shape of this cam H depends upon a number of factors which are more conveniently discussed hereinafter. To the speed shaft 54. which as hereinbefore explained is turned to different positions by the speed responsive device S, is fastened a speed arm 136 extending downwardly at one side of the cam H. In the lower end of this arm 136 is fixed a pivot stud 137, and on this stud is pivotally connected the lower end of a floating lever 138. The upper end of this floating lever 138 carries a freely revolvable roller 139 which bears against the outer edge of the cam. H.

It will be observed that the lower end of the floating lever 138 assumes different post tions corresponding to the actual speed of the vehicle at that time, and that the upper end of this floating lever assumes different positions depending upon the shape of the cam H and its position. The middle point of the floating lever 138,- therefore, takes a position corresponding to the combined action of speed and cam position. The remaining parts of this speed-distance contact unit are designed to open and close certain electrical contacts when the middle point of the floating lever 138 assumes a predetermined position. 4 A

Extending lengthwiseof the instrument compartment is a sector supporting shaft 134; and mounted to turn on .this shaft is a double contact operating sector Sr consisting of a sleeve 140 and two sector shaped plates 141 and 142 integral therewith and each counterweighted and balanced (see Figs. 8 and 9). A connecting link 143 is pivotally connected at one end to the middle point of the floating lever 138 and at its other end to this contact operating sector Sr, so that as the middle point of this floating lever shifts to the left from the position shown in Fig. 8, this sector is rocked clock wise. A torsion spring 144 on the shaft 134 (see Fig. 3) is fastened at one end to the sector Sr and at the other end to a collar 145 fixed on said shaft. This spring 144 exerts a pressure tending to move the sector Sr counter-clockwise, and in addition to taking up all lost motion, holds the roller 139 tight against the edge of the cam H.

Referring to Fig. 8, a segmental plate 146 having its outer edge formed with two arcuate portions connected by a cam incline 146, is adjustably su ported on the sector plate 141 by screws 14 passing through slots 148 in said plate. By adjustment of this plate 146, the cam incline thereof may be shifted to assume the desired angular relation with respect to the sector 141, for the purposes hereinafter explained.

Extending along the wall of the mstrument compartment is a contact supporting shelf or. bracket 150; and on this shelf are supported a number of pairs of movable contact fingers, some normally open and some normally closed. The construction of these fingers, and their manner of support, is similar, and an explanation of one pair will suffice for all.

Referring to Fig. 8, a pair of normally closed contact fingers 151152 are shown which are operated by the plate 141 of the sector Sr. Generally speaking, these contact fingers are pivotally supported at their lower ends and are spring pressed in one direction against stops, the distance between one finger and its stop being greater than that of the other finger, so that as one finger is rocked back and forth the contacts on the upper ends of these fingers are separated or rought together. In the particular construction illustrated, each of the contact fingers 151 and 152 is formed with spaced integral cars at the lower end which are pivotally connected by a suitable pin or stud to a supporting standard 153. The standard 153 has a bolt-like extension 153 which passes through an insulating sleeve 154 in the bracket or shelf 150 and is clamped between two blocks 155 of insulating material by nuts 156, this extension and said nuts constituting a convenient'binding post for the attachment of wires. The standard 153 has an upright portion substantially parallel with its corresponding contact finger; and fixed in the upper end of this portion is a pin or stud 157 which passes through a larger hole in said finger. On the pin 157 is a compression coil spring 158, located between the contact finger and a washer 159 on said pin, said washer being held in place by a small cross pin, or the like. When the contact fingers 151 and 152 are pressed together, as shown, the left hand finger 151 is at a greater distance from the upright extension of its standard 153 than is the case with the other finger 152. The fingers 151 and 152 have suitable cooperating contacts at their upper ends, one of these contacts being preferably of non-fusing or refractory material, such as carbon, while the other contact is of high grade silver, or the like.

In the arrangement shown, the carbon button 160 is fixed in a cup having a stem adjustably connected to the upper end of the finger 151, while the resilient silver tip 161 is riveted to the upper end of the finger.

152. The lefthand finger 151 has secured thereto, as by rivets, a U-shaped bracket or hanger 162 which has a roller 163 journaled in its outer end and bearing against the edge of the segmental plate 146. Either the roller 163 or the hanger 162 is made of suitable insulating material so as-to insulate the finger 151 from the sector Sr.

When the sector Sr is turned clockwise, as shown in Fig. 8, far enough to bring the cam incline 146 on the plate 146 opposite the roller 163, the contact finger 151 is shifted to the left by its spring 158 until arrested by engagement with its standard 153; but since the finger 152, as previously explained, cannot move as far, the contacts at the up per ends of these fingers are separated and the circuit theretlirough is broken. ;When the sector is turned again counter-clockwise, the roller 163 is forced to the right, bringing the contacts of the fingers 151-152 again into contact and reclosing the circuit.

.The contact fingers 174 and 175 in Fig. 9 are constructed and supported the same as the fingers 151 and 152 in Fig. 8, but the segmental plate 176 is so shaped as shown, and the parts are so proportioned, that these fingers 174175 have their contacts normally separated and are closed when the sector Sr is moved clockwise to the position Where the roller 163 is forced toward the right. By comparison of Figs. 8 and 9 it will be noted that the segmental plates 146 and 176 are shaped so that as the sector Sr is moved clockwise, the fingers 174 and 175 close their contacts before the fingers 151 and 152 open their contacts, this difference being variable by adjustment of these plates.

In other words, the normally open contacts of Fig. 9, suitable fpr use for the control of a warning signal, for example, are closed at a lower speed limit or after a less distance of travel than that required to open the contacts shown in Fig. 8, the latter being suitable for governing a brake-setting appllance, for example. In short, by properly proportioning or adjusting the parts, the contact construction shown in Figs. Sand-9 may be adapted to open or close circuits for any desired predetermined position of a cam and speed arm.

Distance contact unit-In Fig. 10 18 shown a typical arrangement of contacts which are opened after a predetermined distance of travel of the train following the initiation of one of the distance measuring or cam shafts. The contact fingers are constructed the same as previously described, and may be normally open as shown or may be normally closed. 7

To the lefthand contact finger 167 is fastened a U-shaped hanger 169 which is pivotally connected to a link 170, the other end of which is pivotally connected to a rock arm 171 journaled on the sector supporting shaft 134. The upper end of the rock arm 171 is bifurcated and carries a freely revolva- -ble roller 172 which bears against the edge of a disc 173 secured by a set screw or the like to the high cam sleeve 86. The disc 173 has-a portion of its periphery cut away, leaving two inclined shoulders 173 It will be evident that as the high cam sleeve 86 is turned in either direction from the normal or initial position to a predetermined :extent, one. or the other of the shoulders 173 depending upon the direction of rotation of the disc 173, strikes the roller 172 and shifts the rock arm 171 to the right to, close the contacts of the fingers 167168. The spacing between the shoulders 173 determines the distance of travel required to open or close the contacts. The contact fin- 8. These contacts are governed directly by the speed responsive device S and control suitable circuits by breaking them when the speed of the train exceeds a certain amount, which in the particular instance may be assumed to be two miles per hour. The contact finger 193 in this instance has riveted thereto a bracket 194 bifurcated and containing a roller 195. The extreme righthand end of this bracket 19.4 is similarly provided with a small roller 196, which engages the spring finger 191 engaging the finger 190. The speed shaft 54 has a speed arm 198 pinned thereto and has its free end pivotally connected to a connecting rod 199, which has its other curved end pivotally connected to a sector, conveniently called a two-mile per hour sector and designated 2m. p. h.

This sector 2 m. p. 11. has adjustably fastened thereto a cam plate 201, similar to the cam plate shown in Fig. 8. It will be noted that when the arm .198 is rotated clockwise through a small angle, the sector 2 m. p. 11. is similarly rotated and causesthe roller 195 to ride into the cutaway portion, thereby allowing the contacts 190 and 192 to be moved away from the contacts 191 and 193, respectively, by the action of springs 158. A plurality of speed contacts of this type are. provided in this system for opening or closing circuits, as the case maybe, at the desired speeds. I

Relays.Certain of the various relays used in the present train control system'are preferably mounted below the shelf 150, and are provided with contacts similar to those heretofore described mounted on and insulated from this shelf. In Figs. 12 and 13 have been shown the push button relay PBR, its purpose and. functions to be more fully described hereinafter. This relay comprises a core 204 1nounted in a U-shaped member 205 made of soft iron, and supported on a bracket 206 directly below the shelf 150. A coil 207 is held on this core 204 between the pole piece 208 and the member 205. A journal block 209 is riveted to the member 205 for pivotally supporting the armature 210.,

This armature 210 is shown in its normal attracted positionwith the coil 207 energized and the armature engaging a non-magnetic residual pin 211.

To the top end and above the pivotal support of the armature is riveted an arm 212,

aving its top end provided with a rivet 213 UNI (ill

containing spacing sleeves 214' (see Fig. 13) to maintainthe ends of, the U-shaped operator 215 adjacent the heads of the rivet 213. The operator 215 of general U-shape has its closed end perforated to receive a guide pin 216. This operator 215 is normally urged toward the right, as shown in Figs. 12 and 13, by a compression spring 217, this spring 217 being held in position on the guide pin 216 by the nut and Washer 218. Between the sides of the U-shaped operator 215 is pivotally supported a roller 220 of insulating material, and this roller 220 engages the contact springs 222 and is adapted to complete a circuit by the back contacts 223 engaging contacts 224 when the coil 207 is deenergized, due to the action of the spring 217 urging the U-shaped operator 215 toward the right, as shown in Figs. 12 and 13. It shouldbe understood that by a slight modification, front contacts may be provided, that is, contacts which are closed when the coil 207 is energized, instead of back contacts such as illustrated in Figs. 12

. and 13.

I nfluence communicating means.

should be kept in mind when considering the trackway apparatus illustrated in Fig. 14.

In Fig. 14 have been illustrated the track rails 228 of the block J and the adjacent 'ends of blocks I and K of the usual wellknown block si aling systemhaving -certain additional g dvices superimposed thereon, the direction of traffic being from left to right as indicated by the arrow. Each of these blocks is equippel substantially the same, and therefore 11 e parts thereof have been designated by the same reference characters with distinctive exponents.

Each of the blocks is provided with a suitable three-position semaphore signal conventionally shown at Z which is controlled by the track relay T of the block at the entrance to which it is located, this control being in part responsive to traffic conditions in the next block in advance b reason of the reversal of the track circuit current by the signal in advance. The operating mechanism, hold-clear devices, and circuits for controlling the signals are omitted to simplify the description of the present invention.

Each of the signals Z .is equipped with circuit controllers of well-known construction which have been illustrated in conformity with established convention. -According to this invention, the circuit control er is assumedto correspond to a pivoted switch arm shown horizontally by full lines (in alignment with the blade of the corresponding signal) which swings through degrees and completes a circuit through the arc of movement indicated by heavy lines or at the points shown by dots. For example, the circuit controller 242 closes a circuit in the vertical or 90 degree position of the signal, at t the inclined or 45 degree position of the signal, and points in between; and this circuit controller also closes another pair of contacts or a circuit in the horizontal or zero degree position of the signal. It may be explained here, without pointing out the specific wiring connections, that the two circuit controllers for the signals Z are in effect pole-changing contacts.

The track relay T of the block J has its track winding under normal clear traffic conditions, as illustrated in Fig. 14, energized by track or loop circuit current supplied from the secondary winding of the transformer 230 The circuit for energizing this track winding may be traced as fol lows :beginning at the secondary winding of the track transformer 230 wire231 the usual impedance 232 wire 233, track rails 228 of the block J through the track windin of the track rela T back to the other real 228 of the block wire 234 back to the szcgcpndary winding of the track transformer The primary winding of the track transformer 230 is energized by the secondary winding of thetransformer 235 through a circuit comprising wire 2%, signal circuit controller 237, wire 239, primary winding of the track transformer 230 wire 240 the signal circuit controller 242 of signal Z and wire 243 back to the secondary of the transformer 235 This transformer is energized from the line wires 244 connected to an alternating current generator 245.

It should be noted that if the signal Z at the entrance of the block K changes from the clear to the caution position, the energizing circuit for the track winding of the relay T will not be changed, but if the signal Z moves still further and to the danger position the relative polarity of the track transformer 230 is changed due to the reverse-l of its primary winding by the movable contacts 237 and 242 operated by the signal Z That is, the current in the track or loop circuit for the block J will flow in the normal direction when the block K in advance is a. clear or caution block, but will be reversed when traflic conditions change to make the block K a danger block.

in the two rails are cumulative.

menace In order to supply current in the rails flowing in the two rails in multiple, suitable high resistance shunts have been bridged be tween the track rails. These resistances will for convenience be called balancing resistances, because current will be fed to or con ducted oil of the middle point of these resistances, thereby causing the currents to divide between the rails substantially equally. The ohmic resistance of these balancing resistances is preferably so high that their shunting effect on the track relay is negligible. In the particular block J shown only four of these resistances are provided. The section of the block extending from the beginning of the block J or point A to the point B is supplied by a transformer 246. This simplex current flows through the two rails 228 in multiple for the section between points A and B through the following circuit:'beginning at the secondary winding of the transformer 246. wire 247 through the balancing resistance 248, through the two rails 228 in multiple. through the balancing resistance 249, wire .250 back to the secondary transformer 246.

A similar simplex circuit is provided for that portion of the block J shown beyond point B, which is supplied by the transformer 251, and comprises the secondary coil of this transformer, wire 252, contact 253 of the track relay T wire 25-1 or 255 depending upon. whether the block in advance is in a clear or caution condition, wire 256, through the balancing resistance 257, through the two rails 228 in multiple, throlugh the balancing resistance 258, wire 259 back to the secondary winding of the transformer 251. It will be noted that this circuit is only broken when the block K in advance is occupied.

Ca worried influence recez'm'n-g apparatu.s.-On the railway vehicle, which has been conventionally illustrated by a pair ofaxles and wheels, are provided suitable laminated magnetic cores for detecting, by magnetic induction, the flow of current in the track rails as shown. These car elements comprise U-shaped cores 260, preferably made of a good quality of laminated iron terminating in enlarged pole pieces 261. These car elements are provided with coils 262. It should be noted that the coils on the front two elements E are wound oppositely so that the voltages induced by currents flowing in opposite directions in the two rails are cumulative, whereas the elements F on the rear of the vehicle have their coils wound alike so that voltages induced in these coils due to current flowing in the same direction It is thus obvious that the front coils E will be able to detect loop circuit current, substantially all of which flows through the axles and does not come under the elements F; whereas the elements F will detect the flow of simplex current which flows in the same direction in both rails in the rear of these two axles illustrated.

The circuit including the elements E and the circuit including the elements F lead to asuitable amplifying apparatus convert t-Yonally shown by the rectangle Q3. This amplifying apparatus may take various forms,.but pre erably includes well-known three-element vacuum tubes or audions which amplify the voltages induced in the circuits including these car elements. The current due to the front elements E is amplified and conducted through a winding 263 of the polyphase induction type main relay MR shown, whereas the current flowing due to voltages induced in the car elements F is similarly amplified andconducted through the other winding 264 of this relay MR. If desired, a relay of the dynamometer type may be used instead of the induction type relay MR shown. I

As shown in Fig. 14, the vehicle is moving in the block I under clear trafic conditions and the relay is energized to hold its' contact 265 in the extreme lefthand position. If the phase relation of the two cur rents tlowin in the windings of thisrelay MB is reversed, this contact 265 is moved toward the right as indicated by the dotted line 266; and if this relay is deenergized, because one or the other orboth of these currents are cut off, the contact 265 will assume the pendent position as shown by the dotted line 267, due to the usual counter-weighting of the relay.

Operation of influence oonwmum'oating meqms.-Since the entire trackway through train control territory is provided with both loop circuitand simplex circuit current under clear traflic conditions, the main relay MR maintains its normal energized condi-- tion as shown in Fig. 14.

Let us assume now that the block K in advance of the block I is occupied. With this block K occupied by another train, the signal Z at the entrance to this block K assumes its danger position, thereby movin the circuit controllers 23'? and 24:2 to the position corresponding to the horizontal position of the semaphore. This causes loo circuit current to be fed into the block by the transformer 230 in a reverse direction as compared with what it did when this signal Z was in either the clear or caution position, that is, this transformer 230 will now be supplied by current through the following circuit :beginning at the secondar of the transformer 235 wire 236 circult controller 237 wire 268 primary winding of the transformer 230 wire 269 circuit controller 242 wire'2e t3 back to the secondary of the transformer 235 In practice, the circuit controllers 237 and 242 are parts of a snap circuit controller operated by the signal mechanism, this type of circuit controller being preferred because the circuit would not remain open for an-appreciable time which might affect signals in the rear.

With the block K occupied by another train, the track relay T located at the entrance of this block will be deenergized because this relay is shunted by the axles and wheels of said another train. This deenergization of the track relay T causes the contact 253 to be in the pendent position, thereby leaving the simplex circuit supplied by the secondary of the transformer 251 open. The reversal of the current in the track or loop circiut of the'block J causes the contact 253 of the track relay T at the entrance to this block J to assume the reverse position (shown dotted), thereby moving the signal Z to the caution position by means and in a manner well-known by those skilled in the art.

As the train equipped with the apparatus just described moves through the block I with the block K occupied, the relay MB is maintained in its normal position as illustrated. As this vehicle, however, moves into the block J, this relay MR assumes the reverse position. This is due to the .fact that the loop circuit current in the block J has been reversed, as just explained, thereby causing the current in the coil.263 to lag behind instead of lead the current in coil 264 or vice versa, thus reversing the torque in the relay MR and causin it to assume and indicatethe caution tra c conditions exist- 1ng.

Let us assume now that this vehicle passes the point B in the block J. As this point B is passed, the relay MR drops its contact 265 to the pendent or neutral position, because there is no simplex current flowing in the rails 228 beyond the point B. This position of the relay MR may be assumed to be the danger position to indicate that either the simplex or the loop circuit current is entirely absent, due to a train ahead, broken rails, an open drawbridge, or the like.

As the train continues 'to travel from'the block J into the block K (possibly ata reduced speed), the position of the main relay MR will not change. Al ough simplex current is present in the rst section of the block K, no loop circuit current is resent because this latter current is shunted t rough the axles of the train ahead, and does not reach the rear end of the block K.

It should be noted that any change of traffic conditions ahead will be immediately manifested on a following train, because this train is continually receiving current under clear or caution trafiic conditions; and

if no current is received in either or both of the windings of the main relay M R, danger traffic conditions are known to exist.

Operation of the system.

Circuit diagram-In Fig. 15 has been shown a simplified circuit diagram of the car-carried apparatus embodying the present invention. The various relays, speed-distance contacts, distancecontacts, speed contacts, cam starting magnets, and the like, have been shown connected in a complete circuit diagram embodying one form of the present invention. In this diagram, the various contacts operated by the various relays are shown directly under each other and connected by a dotted line. Similarly, the speed contacts which are all operated by the same speed shaft, and the distance contacts which are operated by either the high cam sleeve or the low cam shaft, have been shown connected by a dot and dash line to show this relation between certain of the cams. Similarly, the high to medium s eed cam H is shown connected to the hig cam starting magnet HCS by a dot and dash line, whereas the mediulnto low cam L is shown connected by a dot and dash line to the low cam starting magnet LCS. p

In this circuit diagram, the car-carried aparatus has been shown divided into certain groups. These groups are shown separated by iorizontal dotted lines, and in this circuit diagram the several devices have been shown in their normal clear trafiic condition with the vehicle running at a speed somewhere between, say, forty miles per hour and the maximum speed that the train is permitted to run without an automatic brake application, which for convenience is assumed to be sixty miles per hour. The various electro-responsive devices may be energized by any suitable source of energy supply available, this energy supply preferably being direct current received from a generator or some other suitable source of supply, a battery 271 having been illustrated for this purpose. As shown, the various devices are connected between the bus wire 272 and the return wire 273, each group of devices being shown maintained electrically independent of the other groups as much as possible for the purpose of simplifying the wiring diagram.

Nomal c0nditz'0ns.-The main control relay MR controls repeater relays N and R, which in turn control the various :ab signals and car-carried electro-responsive devices. Under the normal clear position of the relay MR, both of these repeater relays N and R are energized. The normal repeater relay N is energized through the following circuit :-beginning at the battery 271, bus wire 272, wires 275 and 276, contact 265 of the main relay MR, wires 277 and 278, windlUU reaaeee ing of the repeater relay N, wires 279 and. 280, return wire 273 back to the battery 271. The reverse repeater relay R is energized under clear tratfic conditions by the front contact of the normal rela N, through a circuit which may be traced as follows :beginning at the battery 271, bus wire 272, wires 275 and 281, front contact 282 of the normal relay N, wires 283 and 284, Winding of the reverse relay R, wires 285 and 280, return wire 273 back to the battery 271.

The relays N and R are preferably slow acting, so that the movable contact 265 of the main relay MR will have assumed its caution position (shown dotted) before the normal relay N has opened its front contact 282, and the reverse relay R has had time to open its front contacts. This slow action is desirable because the reverse relay R would otherwise be momentarily deenergized if the normal relay N should break the energizing circuit for relay R at the front contact 282 before this energizing circuit would again be completed by the movable contact 265 of the main relay MR in its reverse dotted position.

The various positions of the contact 265 of the main relay MR corresponding to the various traffic conditions have been heretofore pointed out. It should now especially be noted that under clear traffic conditions with the contact 265 of the main relay MR in the extreme lefthand position, a circuit for energizing the normal repeater relay N is completed; and with the relay N energized, a circuit for energizing the reverse repeattr relayR is completed, thus maintaining both of the relays N and R in the energized position under clear trafiic concutions. Under caution trafiic conditions, with the relay MR assuming the other extreme position, the relay R only is maintained encrgized; and with the main control relay MR in the deenergized position, both the normal relay N and the reverse repeater relay R, are deenergized. Also, under this the normal condition of the main relay MR, the green cab-signal lamp Gr is lighted as more clearly pointed out under Cab signalsl.

Under normal clear traffic conditions, the penalty relay PR (found in the penalty group. Fig. 15) is energized by the following tircuite-beginning at the battery 271, bus wire 272, wires 301 and 302 through the back-contact 303 of the reverse relay R in multiplewith the cam contact 304 operated by the low penalty cam LP. wires 305 and 306, the front contact 307 of the normal re lav N in multiple with the cam contact 308 operated by the high penalty cam HP, wires 309 and 310, front contact 311 of the penalty relay. wires 312 and 313. winding of the penalty relay PR. wire 314 back to the common return wire 273 leadina to the battery 271.

The high cam starting magnet HOS (cam starter group) is under normal clear traflic conditions energized through the following circuit-beginning at the battery 271, bus wire 272, wire 315, back contact 316 of the push button relay PBR, wires 317. 318and 319, front contact 320 of the normal relay N, wires 321- and 322, winding of the high cam starting magnet HUS, Wires 323 and 324 back to the common return wire 273 connected to the battery 271.

The low cam starting magnet LCS is normally energized through a similar circuit as follows :-beginning at the battery 271, bus wire 272. wire 315, back contact 316 of relay PBR', wires 317 and 325, front contact 326 of the reverse relay R, wires 327 and 328, winding of the low cam starting magnet LCS, wires 329 and 324, through the common return wire 273 back to the battery 271.

With the vehicle traveling along the track under normal clear trafiic conditions at a speed as heretofore mentioned (above forty miles per hour but below the maximum permissive speed), the electro-pneumatic valve E. P. V. (E. P. V. and warning signal group) is maintained energized through the following circuit :-beginning at the battery 271. bus wire 272, wires 330 and 331, front contact 332 of the penalty relay PR, wires 333, 334 and 335, front contact 336 of the reverse relay R, wires 337 and 348. speeddist-ance contacts 151 and 152 of the high cam H, wires 338 and 339, front contact 340 of the electro-pneumatic valve E. P. V., wires 341 and 342, winding of the E. P. V., wire 343 and common return wire 273 back to the battery 271.

It should be noted that the front contact 336 in the circuit just traced is shunted by partial circuit (wires 344 and 346, contacts 151--152 of the low cam L and wire 345) including contacts operated by the low speed-distance cam L, so that when the repeater relay R is deenergized this contact 336 opens (removes the shunt) and puts these two pairs of speed-distance contacts in series in a circuit including the E. P. V. Under this condition of the apparatus, the

vE. P. V. will be deenergized tocause an automatic application of the brakes if the speed exceeds that enforced by either of the speed-distance cams H or L; whereas if the contact 336 is closed, the speed limit set up by the speed-distance cam H only is en forced.

The electro-pneumatic brake applying means E. P. V. is of the normally energize type, and may take an one of a variety of forms well known in tne art. For instance, it may include suitable means for actuating the usual engineers valve to apply the brakes in a manner so that the engineer is unable to forestall or prevent its taking effect, that is, may actuate the valve handle with a force which the engineer is unable to oppose; or actuate the ,valve itself and simultaneously therewith disconnect the handle from the valve at least as far as operation toward the release position is concerned. Since various devices suitable for this purpose are known in the art, and since the present invention is more particularly directed 110- means for actuating a brake applying device, this device has been conventionally shown as comprisin an electro-pneumatic valve. this apparatus may be designed so that it will vent the brake pipe to a predetermined extent only, and if this amount of braking already exists prevent its taking efi'ect altogether.

Thus, under normal clear running conditions, both the high and low cam starter magnets HOS andLCS are energized, both the high speed cam and the low'speed cam are in the normal or initial maximum speed position, and the o eration of the brake controlling device E. V. is dependent on the observance of amaximum speed limit of, say,

sixty miles per hour.

Gab signaZs.With the main relay MR energized the repeater relays N and R in the clear traffic condition, and the green lamp Gr is illuminated by the following circuit beginning at the battery 271, bus wire 272, wires 27 5 and 276, contact 265 of the main relay MR, wires 277 and 286, green lamp Gr, wires 287, 288 and 289, the return wire 273 back to battery 271.

Under caution conditions, the contact 265 of the relay MR is reversed to the dotted position, interruptin the circuit just traced for the green lamp r, the reverse relay R being kept energized throu h the following circuit :-beginnmg at the attery 271, bus wire .272, wires 275 and 276, movable contact 265 of. the main relay MR, wires 290 and 284, winding of the repeater relay R, wires 285 and 280, the return'wire 27 3 back to battery 271. Under the caution trafiic condition of the main relay MR, the yellow lamp Y is illuminated by. current flowing through the following circuit :beginning at the battery 271, bus wire 272, wires 275 and 281, contact 282 of the normal relay N, wire 291, front contact 292 of the reverse relay R, wire 293, yellow lamp Y, wires 294, 288 and 289, common return wire 273 back to the battery 271.

If the main relay MR is deenergized on account of danger trailic conditions ahead, the movable contact 265 of this relay drops to the pendent position, thereby deenergizing both the relays N and R. This causes the lamps Gr and Y to be deenergized, as is obvious from the wiring diagram, and causes the red lamp Rd to be lighted through the following circuit :-beginning at the battery 271, bus wire 272, wires 275 and 281, contact 282 of relay N, wire 291, contact 292 Similarly, I

of reverse relay R, wire 295, contact 296 of the relay NS, wire 297, red light Rd, wires 1 298, 299 and 289, common return wire 273 back to the battery 271.

Maximum speed restriction car appcmaitui normal) .With the high spec -distance cam H in the normal position (.see Fi s. 8 and 15), a certain predetermined speed imit will be set up which if exceeded will cause an automatic brake application. Referring more 1particularly to Fig. 8, assuming the cam toremain in its normal position as shown, it is noted (see Figs. 3 and 4) that the speed arm 136 will be moved in a clockwise direction as the speed of the vehicle is increased. This clockwise movement of the speed arm causes the lower end ofthe floating lever 138 to be moved toward the left, it being fulcrumed by the roller 139 on the high cam H, and moves the link 143 toward the left, thereby rotating the sector Sr in a clockwise direction. Obviously, if the speed is increased to a predetermined value {lassumed to be sixty miles per hour), the ro ler 163 rides down the cam incline of the sector 146, thus causing the contacts 151152 to be opened (see Fig. 15) thereby breaking the stick circuit for the E. P. V. and causing an automatic application of the brakes in a. manner as heretofore described. Before an automatic brake application is effected in the manner just described, a suitable warning signal will be operated, as more clearly pointed out hereinafter.

Acknowledgment of caution signal-Let us assume that a car equipped with the apparatus illustrated in Fig. 15 is moving along the trackway and is just about to pass a signal at caution. If the engineer or operator is aware of this fact and attends to his duties, he will acknowledge this change of traflic conditions by making a manual act in recognition of his knowledge of changed trafiic conditions, which in the present embodiment of the invention consists in pressing the push button PB before this change of trafiic conditions is manifested by the reversal of the main relay MR. By pushing this button PB, the push button relay PBR is energized through a circuit obvious from the drawings and including this relay and push button. which, among other things, (including the momentary picking up of relays NS and L-Ack) closes the front contact 350 which completes a pick-up circuit for the high speed acknowledging relay H-Ack. This circuit comprises wires 352, 353 and 354. make-before-break contact 351, wires 347 and 412, front contact 350, wires 413 and 358 winding of the relay H-Ack, wires 359 and 360. With this acknowledging relay H-Ack picked up, dropping of the normal relay N causes its make-before-break contact 351 to drop, thereby closing a stick circuit through the acknowledging relay H-Ack and main- 

